Advanced Biology: Muscle Contraction and Skeletal Systems

Muscle Contraction

Generates movement by exerting force in animals.

Locomotion

Entire animal moves relative to its environment.

Partial Movement

One body part moves relative to another part.

Biomechanics

Physics application to study organism mechanics.

Sliding-Filament Model

Filaments slide past each other during contraction.

Muscle Tissue

Composed of slender fibers for contraction.

Muscle Fiber

Long, thin muscle cell containing myofibrils.

Myofibrils

Threadlike structures containing sarcomeres.

Sarcomeres

Units in myofibrils that shorten during contraction.

Actin

Thin filament protein involved in muscle contraction.

Myosin

Thick filament protein that interacts with actin.

Calcium Ions

Trigger contraction by binding to troponin.

Actin-Myosin Interaction

Four-step cycle enabling muscle contraction.

Action Potential

Triggers acetylcholine release for muscle activation.

Acetylcholine Receptors

Open channels, depolarizing muscle cells.

T Tubules

Transmit action potentials into muscle cells.

Sarcoplasmic Reticulum

Releases calcium ions for muscle contraction.

Smooth Muscle

Involuntary, unstriated muscle found in organs.

Cardiac Muscle

Striated muscle with intercalated discs for synchronization.

Skeletal Muscle

Voluntary muscle attached to skeleton for movement.

Intercalated Discs

Connect cardiac muscle cells, synchronize contractions.

Troponin

Protein that regulates actin-myosin interaction.

Tropomyosin

Blocks myosin binding sites on actin.

Voluntary Mechanism

Controlled by somatic motor neurons for movement.

Spinal Cord Injuries

Damage to motor neurons causing paralysis.

Force Dependence

Influenced by fiber types and usage patterns.

Slow Fibers

Red fibers, high myoglobin, resist fatigue.

Fast Fibers

White fibers, low myoglobin, fatigue quickly.

Intermediate Fibers

Pink/red fibers, mix of energy systems.

Endurance Muscles

Higher proportion of slow muscle fibers.

Burst Activity Muscles

Higher proportion of fast muscle fibers.

Fiber Training Effects

Increases mitochondria and blood vessels, not fiber types.

Length Change

Determined by number of sarcomeres in series.

Force Exertion

Proportional to sarcomeres arranged side-by-side.

Parallel Fibers

Maximize length change during contraction.

Pennate Fibers

Maximize force through more sarcomeres.

Voluntary Control

Conscious muscle control via somatic PNS.

Involuntary Control

Unconscious muscle activity via autonomic PNS.

Multinucleate Muscle

Skeletal muscle cells with multiple nuclei.

Uninucleate Muscle

Smooth and cardiac muscles with one nucleus.

Striated Muscle

Skeletal and cardiac muscles with sarcomeres.

Unstriated Muscle

Smooth muscle lacking sarcomere alignment.

Hydrostatic Skeleton

Fluid-filled structure providing support and movement.

Endoskeleton Structure

Internal rigid elements like bones and cartilage.

Exoskeleton Composition

Rigid external covering made of chitin or minerals.

Calcium Homeostasis

Bones regulate calcium levels in the blood.

Osteoporosis

Condition of reduced bone mass affecting strength.

Hydrostatic

Fluid or soft tissues under compression.

Endoskeleton

Internal skeleton made of bone and cartilage.

Exoskeleton

External skeleton made of chitin or calcium carbonate.

Antagonistic Muscle Groups

Muscles that work against each other for movement.

Pennate Muscle Arrangements

Muscle fibers arranged for increased force production.

Continuous Growth

Uninterrupted growth characteristic of hydrostatic organisms.

Bone Remodeling

Ongoing replacement of old bone tissue.

Molting

Shedding of exoskeleton for size expansion.

Modes of Locomotion

Different movement types: land, water, air.

Biomechanics

Study of movement principles and mechanics.

Active Contractile Properties

Tissue properties critical for generating force.

Passive Material Properties

Tissue properties important for force transmission.

Walking Mechanics

Similar to an upside-down pendulum in motion.

Running Mechanics

Resembles a bouncing ball utilizing tendon energy.

Ichthyostega

Fossil analyzed for insights on walking ability.

Visual Observation

Using sight to analyze movement and function.

Eadweard Muybridge

Pioneer in capturing motion sequences in photography.

Newton's Third Law

For every action, there is an equal reaction.

Buoyancy

Reduction of gravity's effect in water.

Surface Area-to-Volume Ratio

Decreases as animals grow larger.

Energy Cost of Locomotion

Larger animals expend less energy per gram.

Phineas Gage

Case study of brain damage affecting personality.

Force Plates

Devices used to study ground forces during locomotion.

Broca's area

Region in left hemisphere for speech production.

Hippocampi

Brain regions crucial for memory formation.

Prosopagnosia

Inability to recognize faces due to brain damage.

Neuroplasticity

Brain's ability to adapt after injury.

EEG

Non-invasive method to read brain activity.

ECoG

Invasive electrodes placed on brain surface.

Intraparenchymal

High-resolution electrodes implanted inside the brain.

First Night Effect

Left hemisphere remains vigilant in new environments.

Suprachiasmatic nucleus (SCN)

Regulates circadian rhythms as biological clock.

Adenosine

Builds up during wakefulness, creates sleep pressure.

Grip Strength Experiment

Tested ATP's effect on muscle contraction strength.

Cardiomyocytes

Heart muscle cells that contract synchronously.

Muscle Fibers

Types include slow twitch, fast twitch, and intermediate.

Cellular Respiration

Aerobic process producing 38 ATP per glucose.

Anaerobic Respiration

Produces 2 ATP per glucose without oxygen.

Slow Twitch Fibers

Use aerobic respiration, high myoglobin, low glycogen.

Intermediate Fibers

Faster contractions, use both aerobic and anaerobic.

Caffeine

Blocks adenosine signaling, delaying sleepiness.

Lobotomy

Surgical procedure removing hippocampi to stop seizures.

Facial Recognition

Involves specific neural activity for identifying faces.

Hemispheric Sleep

Birds keep one eye open for vigilance.

Fast Twitch Fibers

Largest muscle fibers, fatigue quickly, anaerobic.

Anaerobic Glycolysis

Energy production without oxygen, used by fast twitch.

ATP Hydrolysis

Rapid breakdown of ATP for energy.

Glycogen Reserves

High storage of glycogen in fast twitch fibers.

Calcium Phosphate

Main form of calcium in bones.

Calcitonin

Hormone that lowers blood calcium levels.

Parathyroid Hormone

Hormone that raises blood calcium levels.

Kidney Stones

Possible consequence of high blood calcium.

Osteoporosis

Condition caused by low calcium, weak bones.